PVM
PVM (Parallel Virtual Machine) is a toolkit currently used to implement parallel applications on heterogeneous computers.
The PVM environment provides primitives for process creation and message passing that can be incorporated into existing procedural languages.
To create n copies of a process
nump = pvm_spawn("proc", …, …, n, pids);
PVM primitives for message passing are
pvm_send(pid, mess); pvm_recv(pid, mess);
pvm_mcast(pids, mess); pvm_bcast(pids, mess);